title: Simulation-based particle swarm optimization and mechanical validation of screw position and number for the fixation stability of a femoral locking compression plate.
abstract: Locking compression plates (LCPs) have been used to fix femoral shaft fractures. Previous studies have attempted to identify the best LCP screw positions and numbers to achieve the fixation stability. However, the determined screw positions and numbers were mainly based on the surgeons' experiences. The aim of this study was to discover the best number and positions of LCP screws to achieve acceptable fixation stability. Three-dimensional numerical models of a fractured femur with the LCP were first developed. Then, the best screw position and number of LCPs were determined by using a simulation-based particle swarm optimization algorithm. Finally, the results of the numerical study were validated by conducting biomechanical tests. The results showed that the LCP with six locking screws resulted in the necessary fixation stability, and the best combination of positions of locking screws inserted into the LCP was 1-5-6-7-8-12 (three locking screws on either side of the bone fragment with two locking screws as close as practicable to the fracture site). In addition, the numerical models and algorithms developed in this study were validated by the biomechanical tests. Both the numerical and experimental results can provide clinical suggestions to surgeons and help them to understand the biomechanics of LCP systems.
authors.affiliation: Department of Orthopaedics, School of Medicine, College of Medicine, Taipei Medical University and Hospital, Taipei 110, Taiwan, ROC.
authors.forename: Chian-Her
authors.initials: CH
authors.lastname: Lee
authors.affiliation: Department of Orthopaedics, School of Medicine, College of Medicine, Taipei Medical University and Hospital, Taipei 110, Taiwan, ROC; Department of Orthopedic Surgery, Shin Kong Wu Ho-Su Memorial Hospital, Taipei 111, Taiwan, ROC; College of Medicine, Fu Jen Catholic University, Taipei 242, Taiwan, ROC.
authors.forename: Kao-Shang
authors.initials: KS
authors.lastname: Shih
authors.affiliation: Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan, ROC. Electronic address: hsucc@mail.ntust.edu.tw.
authors.forename: Ching-Chi
authors.initials: CC
authors.lastname: Hsu
authors.affiliation: Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan, ROC.
authors.forename: Tomas
authors.initials: T
authors.lastname: Cho
mesh_terms: D001860:Bone Plates; D001863:Bone Screws; D005264:Femoral Fractures / Q000601:surgery; D005269:Femur / Q000293:injuries* / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D008422:Materials Testing; D055595:Mechanical Phenomena; D008962:Models, Theoretical; D015203:Reproducibility of Results
keywords: Fixation stability; Locking compression plate; Optimization; Screw position